Semiconductor light emitting devices emit light through the recombination of electrons and holes when a current is applied thereto and are commonly used as light sources due to various advantages thereof such as low power consumption, high levels of luminance, compactness, and the like. In particular, after the development of nitride light emitting devices, the utilization thereof has been greatly expanded and nitride light emitting devices are commonly employed as light sources in backlight units used for displays, general illumination devices, electrical systems, and the like. Various attempts have been made to improve the characteristics of semiconductor light emitting devices. In particular, a need exists for the development of an electrode structure improving luminance efficiency and lowering an operational voltage by evenly distributing (or spreading) currents within light emitting devices.